1. Field of the Invention
The present invention relates, in general, to a method of measuring the height of a foot arch during a process of manufacturing arch supports equipped in shoes and, more particularly, to a method of measuring the height of a foot arch precisely and easily using two essential height measurements of the foot arch.
2. Description of the Prior Art
A foot arch is the raised curve on the bottom of the foot and relieves external impact applied from the ground to the foot during walking or running. The foot arch also allows a person to more easily, smoothly and effectively walk or run while relieving fatigue of the feet.
The feet of people are different in shape of the arch due to various physical conditions of people and are classified into three types; a normal foot, a flat foot, and a hollow foot, in accordance with the height of the foot arch. The flat foot is free from such an arch or has a negligible arch, and such a foot fails to effectively relieve the external impact during walking or running and prevents a person from easy or smooth walking or running on the ground. Therefore, the flat foot causes the person to easily and quickly experience fatigued feet during exercising, thus reducing the exercising efficiency.
How to support the foot arch properly is considered as an important factor in a process of manufacturing shoes. In a shoe, the foot arch is generally supported by an arch support, made of leather felt or rubber foam, fixed on an inner sole, thereby to evenly support the weight of a person applied to the feet while standing, walking or running. When the foot arch is supported by a proper arch support, the health and function of the foot is improved.
Since an arch support manufactured imprecisely causes the feet to be undesirably deformed and to become sore, the arch support has to be designed precisely under consideration of the anatomical structure and physiological function of the feet.
Incidently, it is very difficult to measure the height of a foot arch precisely and to produce an arch support precisely because the foot arch has an atypical shape.
A two-dimensional method of estimating the height of a foot arch is known to those skilled in the art. The two-dimensional method consists of four steps. Of the four steps, the first step is to obtain a first footprint by putting an inked foot upon a test paper while a person is sitting on a chair and the weight of the person is not being applied to the foot. The second step is to obtain a second footprint by putting the inked foot upon another test paper while the person is standing up and the weight of the person is being applied to the foot. The third step is to obtain a third footprint by putting the inked foot upon a rubber mat while the person is walking on the mat. Of the above three steps, each of the first and second steps is so-called a "static footprint test" in the field, while the third step is so-called a "dynamic footprint test". The third step is followed by the fourth step wherein the height of a foot arch is estimated with the footprints obtained in the previous three steps.
In the fourth step, the estimation of height is performed by comparing the position of an arch line AR or AR' of the footprints with the position of the reference line Y. In such a case, the reference line Y is a straight line extending from the center of the second toe to the center of the heel end.
The estimation of the height of the foot arch in the fourth step is described in more detail as follows: When the arch line of a footprint does not reach the reference line Y as shown by the dotted line AR' in FIG. 1, the foot arch is estimated to be relatively low. On the other hand, when the arch line of a footprint passes the reference line Y as shown by the solid line AR in FIG. 1, the foot arch is estimated to be relatively high.
The reason why the line Y is used as a base line in the estimation is as follows. The weight of a person is typically concentrated on both the center of the second toe and the center of the heel end during walking or running. Therefore, when a person, wearing shoes manufactured without considering the above-mentioned point, walks or runs on the ground, the weight of the person is concentrated on the side of shoe, thereby causing the person fall down on the ground.
However, the conventional two-dimensional method is problematic in that the estimation of the height of the foot arch using plane footprints may prevent the height of the resulting arch support from coinciding with the actual height of the foot arch.
To solve the problem of the conventional two-dimensional method, a three-dimensional method of obtaining the height of a foot arch was proposed. The conventional three-dimensional method comprises the following three steps. That is, firstly, a variety of foot arch gauges, having different heights and individually having the shape of a foot arch, are provided. Secondarily, a foot arch gauge of the most similar height is selected by comparing the gauges with the actual foot arch one by one. Finally, the height of the selected foot arch gauge is taken for the height of the actual foot arch.
However, according to the conventional three-dimensional method, since it is almost impossible to provide all heights of foot arch gauges for all kinds of feet, a difference occurs between the height of an actual foot arch and the height of a foot arch gauge. Accordingly, the arch support manufactured according to the three-dimensional method fails to support the weight of the person evenly, thereby inducing pain, horniness, and deformation of the feet.